Barrel mechanism for a piston pump

ABSTRACT

A barrel mechanism comprises, with a casing, a rotatable shaft mounted in two bearings supported respectively by two ends of the casing perpendicular to the axis of the shaft, and to which is fixed a plate oblique with respect to the axis, a barrel bearing on the oblique plate, centred about an axis, intersecting the axis of the shaft, on an inclined cylindrical bearing on the shaft and perpendicular to the plate, and a means locking the barrel against rotation, wherein the two ends of the casing are connected by a tie-rod extending along the axis of the shaft in an axial bore in the shaft.

United States Patent [191 Chanlon [451 May 27, 1975 BARREL MECHANISM FORA PISTON PUMP [75] Inventor: Gerard Chanlon, Le Creusot,

[30] Foreign Application Priority Data Dec. 14, 1972 France 72.44532[52] U.S. Cl. 74/60 [51] Int. Cl. Fl6h 23/08; Fl5h 23/10 [58] Field ofSearch 91/499; 74/60; 417/269 [56] References Cited UNITED STATESPATENTS 2,095,316 10/1937 Davis, Jr. 74/60 2,150,162 3/1939 l-lau 74/602,387,908 10/1945 Howard 74/60 2,498,679 2/1950 Hall 74/60 2,926,7353/1960 Cook 74/60 FOREIGN PATENTS OR APPLICATIONS 1,175,467 3/1959France.... 74/60 799,828 4/1936 France ..74/60 Primary ExaminerWilliamL. Freeh Attorney, Agent, or Firm-Cameron, Kerkam, Sutton, Stowell &Stowell [5 7] ABSTRACT A barrel mechanism comprises, with a casing, arotatable shaft mounted in two bearings supported respectively by twoends of the casing perpendicular to the axis of the shaft, and to whichis fixed a plate oblique with respect to the axis, a barrel bearing onthe 0blique plate, centred about an axis, intersecting the axis of theshaft, on an inclined cylindrical bearing on the shaft and perpendicularto the plate, and a means locking the barrel against rotation, whereinthe two ends of the casing are connected by a tie-rod extending alongthe axis of the shaft in an axial bore in the shaft.

8 Claims, 2 Drawing Figures PATENTEDMAYQ? ms sum .mm mm Nm mm SHEETPATENTEU MAY 27 1975 BARREL MECHANISM FOR A PISTON PUMP The object ofthe invention is a barrel mechanism applicable particularly toaxial-piston pumps.

A known pump of this type comprises a pump body having a number ofpistons distributed round an axis and each displaceable in a cylinderparallel with the axis, and a mechanism forming a rotor driven by amotor and having an oblique thrust-face actuating the pistons byrotation about the axis.

In small pumps the oblique thrust-face is a simple circular platelocated in a plane oblique with respect to the axis of rotation and uponwhich the pistons bear directly by means of rods provided with sphericalbearing faces.

In larger pumps, however, it is preferable to connect the pistons to theoblique thrust face by connecting rods. In such a case a barrelmechanism is employed which comprises, inside a casing, a driving shaftrotated about its axis in two bearings supported respectively by twoends of the casing perpendicular to the axis and to which is fixed aplate extending obliquely with respect to the axis of the shaft, and abarrel bearing on the oblique plate and centered about a point on theaxis of the shaft on an inclined cylindrical bearing on the shaft andperpendicular to the plate. In addition the barrel is prevented fromrotating by some means locking it against rotation. Each piston isconnected to the barrel by a connecting-rod articulated to the pistonand to the barrel at a point remote from the axis.

It is clear that because the barrel is prevented from rotating, rotationof the shaft causes an oscillation of the barrel about its centre, theaxis of the barrel, which coincides with that of the inclinedcylindrical bearing, describing a cone about the axis of the shaft. Thisoscillatory motion controls the movement to and fro of the pistons.

Barrel mechanisms are employed for pumps of medium power, but when it isrequired to produce pumps of high power and high pressure crankshaftpumps are generally employed. The disadvantage of these is that they areheavy and bulky.

Barrel mechanisms on the other hand enable a much more rationalarrangement since the motor; the rotor and the body of the pump can bein line. However, the large forces to be withstood by the barrel andtransmitted to the casing have hitherto prevented the production of highpower pumps, particularly if it is desired to limit their bulk and theirweight.

According to the invention there is provided a barrel 3 mechanismcomprising, inside a casing, a rotatable shaft mounted in two bearingssupported respectively by two ends of the casing perpendicular to theaxis of the shaft, and to which is fixed a plate oblique with respect tothe axis, a barrel bearing on the oblique plate, centred about an axisintersecting the axis of the shaft, on an inclined cylindrical bearingon the shaft and perpendicular to the plate, and a means locking thebarrel against rotation, wherein the two ends of the casing areconnected by a tie-rod extending along the axis of the shaft in an axialbore in the shaft.

Preferably the tie-rod is prestressed before the mechanism is put intoservice.

The invention will be more fully understood from the followingdescription of embodiments thereof, given by way of example only, withreference to the accompanying drawings, in which:

FIG. 1 is a longitudinal section of a first embodiment according to theinvention; and

FIG. 2 is a longitudinal section of a second embodiment according to theinvention.

The mechanism shown in FIG. 1 comprises a casing 1 comprising acylindrical wall 10 to which are fixed two parallel ends 11 and 12.Inside the casing 1 is located a hollow shaft 2 rotatably mounted at oneend, by a plain ring 21, on a tubular distance-piece 3 arranged on theaxis 20 of the casing and bearing against the two ends 11 and 12 of thecasing.

A tie-rod 4 extending within the tubular distancepiece 3 connects thetwo ends of the casing against which it bears by means of a head 42 anda nut 41 enabling the tie-rod 4 to be kept. under a certain tensionalprestress taken up by the distance-piece 3.

The end 12 of the casing is attached to a pump body (not shown)comprising a plurality of axial pistons distributed round the axis ofrevolution 20. Each piston is connected to a slide 5 moving parallelwith the axis in a cylinder 51 fixed to the end 12 of the casing.

The shaft 2 bears against the other end 11 of the casing by means of athrust-plate 22 integral with the shaft 2, by means of a plainthrust-face 23.

The shaft 2 is driven by the motor (not shown) located adjacent the end11, by means of a reducer comprising an input pinion 6 meshing with awheel 24 fixed to the plate 22. The inner face of the wheel 24advantageously constitutes the second journal for the shaft 2, bearingby means of a plain ring 25 against a cylindrical bearing integral withthe end 11.

The shaft 2 also bears a plate 26 inclined with respect to the axis ofrevolution and a cylindrical bearing 27 perpendicular to the said plate,the axis 270 of which is inclined to the axis of revolution of shaft 2.

A barrel 7 is centred on the cylindrical bearing 27 by means of a plainring 71 and bears against the plate 26 by means of a plain thrust-face72. The barrel 7 is prevented from turning by any means, for example, bya connecting-rod (not shown) articulated to the casing and the lowerportion 73 of the barrel.

The barrel is connected at its periphery to the slides 5 by means ofconnecting-rods 8, by ball-and-socket joints, the ends of theconnecting-rods constituting the male portions 81 of the ball-and-socketjoints, the female portions 82 of which are attached to the barrel 7, ata point remote from the axis of rotation, and to the slide 5respectively.

When the shaft 2 is rotated by the pinion 6 and the wheel 24, the axis270 of the cylindrical bearing 27 describes a cone about the axis ofrevolution 20 and the result is that the barrel 7, being locked inrotation oscillates about the point of intersection between the axes 20and 270.

This oscillatory motion of the barrel is transformed by theconnecting-rods 8 into a to -andfro movement of the slides 5 transmitteddirectly to the pistons of the pump. For a pump of high power the forceswithstood by the barrel are very large. Thus for a pump of 1,000 HP athrust of tons on the barrel must be reckoned on. This thrust is takenup by the oblique plate 26 and transmitted directly through ribs 28 tothe thrust-plate 22 which bears against the end 11 of the casing.

However, the tie-rod 4 has been previously prestressed to a tensiongreater than this thrust of 130 tons, the prestress being taken up at noload by the distance-piece 3. The result is that the thrust exerted bythe slide on the barrel is transmitted to both ends of the casing andtaken up wholly by the tie-rod 4 without extension of the latter andconsequently without deformation of the casing. The casing, and inparticular its sidewall 13, which withstands practically no force, cantherefore be considerably lightened. It will be observed, moreover, thatthe employment of a hollow shaft enables the latter to bear against thedistancepiece by means of an internal bearing and hence the length ofthe shaft to be substantially reduced. Another reduction in the lengthis obtained by the arrangement of the other bearing of the shaft on theinner face of the wheel 24 of the reducer.

Finally the employment of plain rings and thrustfaces likewise enables areduction in bulk and weight of the whole. These rings will, forexample, be of bronze or bimetal selected as a function of the forces tobe withstood.

The space between the two plates 22 and 26 enables shaft balance-weightsto be easily located, enabling rotation without risk of vibration to beobtained.

The employment of the prestressed connecting tierod between the ends ofthe casing enable considerable lightening of the latter. That is, takinginto account the magnitude of the thrusts at high power, a conventionalcasing would have had to be very rigid and very heavy. By taking up theforces without risk of deformation, the tie-rod enables an extremelylight casing to be produced which as shown in FIG. 1 can be composed ofrelatively thin sheet metal 13 provided with longitudinal stiffeners 14.

The employment of plain rings and thrust-faces as in FIG. 1, though itenables additional reduction in weight and bulk of the whole is not,however, indispensable.

Taking into account the working conditions, it may in fact be preferredto employ roller guide and thrust bearings as shown in the embodimentsof FIG. 2, whilst keeping within the allowable limits of weight andbulk.

In this embodiment the barrel 7 is in fact centred by a roller bearing710 and bears against the oblique plate 26 by means of a rollerthrust-bearing 720. Having regard to the thickness of the thrust-bearing720, it has been possible to bring the plate 26 to adjacent the plate 22so that it is formed as one body with the plate 22, whilst leavingclearance for the end 73 of the barrel.

The plate 22 bears against the end 11 of the casing by means of a rollerthrust-bearing 23 and the shaft 2 is provided with an extension rotatingin an outer roller bearing 250 fixed to the end 11. At the other end,however, the shaft2 bears against the distance-piece 3 by means of aninternal roller bearing 210.

It can be seen that the use of roller guide and thrust bearings does notsubstantially affect the weight and bulk of the mechanism.

Of course the invention is not intended to be limited to the details ofthe two embodiments which have just been described. In particular theshapes of the shaft and the various parts could clearly be modified. Themechanism could be adapted for driving any kind of axial piston pumpdirectly or by means of articulated connecting-rods as has beenillustrated.

Finally such a mechanism can be adapted for use not only in a pump butin any means employing the displacement of axial pistons, such as acompressor or a piston engine, the mechanism then serving to transformthe axial displacement of the pistons into rotation of the shaft.

What is claimed is:

l. A barrel mechanism comprising:

a. a rotatable shaft having an axial bore;

b. a casing within which said shaft extends and having endsperpendicular to the axis of said shaft;

c. bearings supported respectively by said casing ends and supportingsaid shaft;

d. a plate fixed to said shaft and extending obliquely with respect tosaid axis of said shaft;

e. a barrel bearing on said oblique plate, centred about an axisintersecting said axis of said shaft, on an inclined cylindrical bearingperpendicular to said plate;

f. means locking said barrel against rotation;

g. a prestressed tie-rod extending along the said axis of said shaft insaid axial bore and connecting said casing ends to absorb axial thruston said barrel, said oblique plate being integral with a thrust plate onthat end of said casing remote from said barrel with respect to saidoblique plate, said thrust plate being fixed to said shaft perpendicularto said axis of said shaft, said tie-rod extending in a tubular distancepiece fixed to said two ends of said casing and extending through saidaxial bore in said shaft.

2. A barrel mechanism as claimed in claim 1, wherein said bearings ofsaid shaft are internal bearings.

3. A barrel mechanism as claimed in claim 1, wherein at least one ofsaid bearings of said shaft is an internal bearing by means of whichsaid shaft rotates on said tubular distance piece.

4. A barrel mechanism as claimed in claim 1, wherein said tie rod isprestressed to a tension which is at least equal to the axial resultantof the maximum forces to be transmitted by said barrel to said thrustplate.

5. A barrel mechanism as claimed in claim 1, wherein said bearings ofsaid shaft are plain bearings.

6. A barrel mechanism as claimed in claim 1, wherein a plain ring isinterposed between said barrel and said inclined cylindrical bearing.

7. A barrel mechanism as claimed in claim 1, wherein thrust faces areinterposed between said barrel and said oblique plate and between saidthrust plate and said end of said casing.

8. A pump comprising axial pistons and a barrel mechanism as claimed inclaim 1 constituting the rotor of the pump, each piston being connectedto a respective barrel by a connecting rod articulated to said pistonand to said barrel at a point remote from said axis of said shaft.

1. A barrel mechanism comprising: a. a rotatable shaft having an axialbore; b. a casing within which said shaft extends and having endsperpendicular to the axis of said shaft; c. bearings supportedrespectively by said casing ends and supporting said shaft; d. a platefixed to said shaft and extending obliquely with respect to said axis ofsaid shaft; e. a barrel bearing on said oblique plate, centred about anaxis intersecting said axis of said shaft, on aN inclined cylindricalbearing perpendicular to said plate; f. means locking said barrelagainst rotation; g. a prestressed tie-rod extending along the said axisof said shaft in said axial bore and connecting said casing ends toabsorb axial thrust on said barrel, said oblique plate being integralwith a thrust plate on that end of said casing remote from said barrelwith respect to said oblique plate, said thrust plate being fixed tosaid shaft perpendicular to said axis of said shaft, said tie-rodextending in a tubular distance piece fixed to said two ends of saidcasing and extending through said axial bore in said shaft.
 2. A barrelmechanism as claimed in claim 1, wherein said bearings of said shaft areinternal bearings.
 3. A barrel mechanism as claimed in claim 1, whereinat least one of said bearings of said shaft is an internal bearing bymeans of which said shaft rotates on said tubular distance piece.
 4. Abarrel mechanism as claimed in claim 1, wherein said tie rod isprestressed to a tension which is at least equal to the axial resultantof the maximum forces to be transmitted by said barrel to said thrustplate.
 5. A barrel mechanism as claimed in claim 1, wherein saidbearings of said shaft are plain bearings.
 6. A barrel mechanism asclaimed in claim 1, wherein a plain ring is interposed between saidbarrel and said inclined cylindrical bearing.
 7. A barrel mechanism asclaimed in claim 1, wherein thrust faces are interposed between saidbarrel and said oblique plate and between said thrust plate and said endof said casing.
 8. A pump comprising axial pistons and a barrelmechanism as claimed in claim 1 constituting the rotor of the pump, eachpiston being connected to a respective barrel by a connecting rodarticulated to said piston and to said barrel at a point remote fromsaid axis of said shaft.